1. Field of the Invention
The present invention relates to a novel room temperature curable organopolysiloxane composition, and particularly to such a composition useful as an FIPG (Formed In Place Gaskets) material for automobiles.
2. Description of the Prior Art
For sealing engine oil used at engine parts, gear oil, automatic transmission oil, etc., oil resistant gaskets or packing made of cork, organic rubbers, asbestos, etc. are used. These materials are disadvantageously troublesome in inventory control and working process, and have a drawback of poor reliability in seal performance.
For this reason, FIPG technique using room temperature curable compositions having good adhesion and heat-resistance, has been used, and workability is being improved. However, the room temperature curable silicone rubber compositions and the cured products thereof are affected by acidic additives such as metallic phosphates, metallic phosphites or the like added to the oils for automobiles, so that rubber properties of the cured products are deteriorated or the adhesion is lowered. Therefore, for the purpose of neutralization of the acidic additives, oxides or carbonates of metals such as calcium, zinc, magnesium or the like are added to the compositions. To prevent rubber properties from lowering in case the polymer chains of the cured products are cleaved by the acidic additive, it has been performed to increase the crosslink density of the cured products.
However, to enhance the performance of the oils, recently, the amount of the phosphorus acidic additives added to the oils have been increased, and a sulfur compound or a molybdenum compound which can not be neutralized with said carbonates is added to oils. Therefore, it is now difficult to achieve a satisfactory level of oil resistance only by the addition of the metallic oxide or the metallic carbonate or the increased crosslink density.